1. Field of the Invention
The present invention relates to an ophthalmic apparatus. More particularly, the present invention relates to an ophthalmic apparatus used in refractive surgery to change (alter) a radius of curvature of a cornea of a patient's eye by corneal ablation.
2. Description of Related Art
There are several types of refractive surgery to change (alter) a radius of curvature of a cornea of a patient's eye by ablating the cornea with an excimer laser beam thereby to correct refractive errors such as myopia, hyperopia, astigmatism and the like. Conventionally, in such types of surgery, the corneal shape, the eye refractive power of the eye and the like are measured before an operation and then the operation is carried out based on the obtained measurement data.
However, in these types of surgery, attention has been paid merely to correction of the refractive power of optics of the eye such that a paraxial focal points is positioned on the retina and quality of the image formed on the retina (influence of marginal rays on the image) has not been taken into account. Therefore, the corneal ablation may not necessarily be carried out properly and patients may not be fully satisfied with their post-operative visions.
In addition, although a radius of curvature of the cornea is properly corrected thereby achieving emmetropization of the optics of the eye, the patient may not always improve the post-operative vision as he expected in case the patient suffers from a disturbance in the nervous system following the retina, the brain or other signal system. Therefore, it is desirable to give sufficient information to a patient and to make him fully understand of the situation before performing surgery.